ToneListen is an audio analysis app for exploring the sound around you — including the near-ultrasonic, high-frequency tones the human ear can't hear. Point your device at any environment and ToneListen analyzes the live audio in real time. It reveals the frequency content of a space and detects high-frequency "tone tags" embedded in nearby audio, music, and media — turning your phone into a portable spectrum analyzer and tone reader. WHAT YOU CAN DO - Analyze any environment: Visualize live sound on a real-time spectrum view and see exactly which frequencies are present, from low rumble all the way up to near-ultrasonic. - Hear tone tags: Detect and decode high-frequency tone tags emitted by speakers, displays, TVs, and other media — including tones above the range of human hearing. - On-device media player: Play tone-safe sample files and watch their spectral content render live, so you can study how tone tags look and behave in different conditions. - Location-aware exploration: Use interactive maps to explore and reference where audio analysis is taking place. HOW IT WORKS ToneListen runs high-resolution frequency analysis entirely on your device. It listens through the microphone only while analysis is active, identifies tone patterns in the incoming audio, and displays the results instantly. Nothing needs to leave your phone for this to work. PRIVACY ToneListen uses the microphone solely for on-device audio and tone analysis. No voice, speech, or ambient audio is ever recorded, stored, or transmitted. Microphone input is processed in real time and immediately discarded. PRICING ToneListen is completely free to use. There are no in-app purchases, no subscriptions, and no paid digital content, features, or services unlocked inside the app. Every feature described above is available to all users at no cost, with no account or payment required. ToneListen is ideal for anyone curious about the sounds and signals in their surroundings — from audio enthusiasts and developers to anyone who simply wants to see and hear what is hiding just beyond human hearing.